Myocardial revascularization is presently accomplished using a laser to create channels in the wall of the left ventricle of the heart to perfuse the ischemic myocardium, thereby supplying blood and oxygen directly to the heart muscle, instead of installing one or more bypasses or using angioplasty to overcome blocked arteries and reinstate adequate blood flow. In the transmyocardial approach, a CO2 laser is used to create channels from the outside of the heart wall to the inside. The channels heal rapidly on the outside, from digital pressure applied to the outside surfaces, leaving blind channels extending from the inside part way through the heart wall. During surgery, the surgeon can see each channel and carefully choose subsequent channel sites with correct spacing between them and avoid the danger of cutting a new channel too close to an existing one.
In the percutaneous approach, a Holmium or excimer laser supplies energy through a fiber optic element in a catheter to the inside of the left ventricle where channels are cut in the heart wall from the inside toward but hopefully never reaching the outside of the wall: unlike channels cut from the outside in using a CO2 laser, channels cut from the inside through to the outside using Holmium or excimer lasers do not heal easily. Thus a channel cut through to the outer wall will cause a serious leak, pouring blood into the pericardium. This requires immediate emergency action, namely, open heart surgery to suture or apply a tamponade to the hole; otherwise the patient will die within a few minutes. Since, when working from the inside out using a catheter, a surgeon cannot see exactly where the fiber optic element is aimed nor can he tell where the previous channels have been cut, he constantly runs the risk of cutting a new channel next to, overlapping or even right on an existing channel, which can result in accidentally cutting right through the heart wall.
Moreover, although others have devised systems for delivering therapeutic or diagnostic agents into the channels, no device exists for simultaneously marking the channels and introducing into the channels a therapeutic or diagnostic agent. See U.S. Pat. Nos. 5,840,059; 5,925,012, and international application PCT/US99/07081 incorporated herein by this reference. Indeed, if the channels cannot be seen, it is difficult to introduce a therapeutic drug into the channels.